Javier, it is very weird, that only 10 connections are closed.
Perhaps you can enable pppoe,debug logs and get the reason, why all the 10 clients were disconnected simultaneously.
Otherwise it is very hard to guess, what could be the reason.
Just curious, do you have RADIUS server for these 300 clients?
Well, maybe because English is not my native language I was not clear. When I say "tens", I refer to 23 one time, 45 next, 30 next and so. (In Spanish the word is "decenas", and allways thought the English word "tens" meant the same).
With some hundreds of users, and the fact that this disconnections happen sparsely and randomly is somewhat difficult to enable full pppoe logs without affecting performance, and then the size of the log file in my server (I log to a server with syslog) gets huge. Anyway, both in RB´s and the server logs, the disconnection cause is "User Request". The same in my Radius logs.
And yes, I use 3 RADIUS servers that get user data from replicated LDAP bases.
Some data that I think could be relevant to this issue.
1) Sample Access-Reply AV Pairs.
Tue Dec 8 00:10:31 2009
Packet-Type = Access-Accept
Mikrotik-Rate-Limit = "128k/256k 130k/258k 129k/257k 3/3 8 32k/32k"
Framed-Routing = None
Framed-Protocol = PPP
Service-Type = Framed-User
2) PPPOE Server Configuration
add authentication=pap default-profile=PPPoE disabled=no interface=\
PPPoEVLAN20 keepalive-timeout=10 max-mru=1480 max-mtu=1480 max-sessions=0 \
mrru=disabled one-session-per-host=yes service-name=XXXX
add authentication=pap default-profile=PPPoE disabled=no interface=VLAN10 \
keepalive-timeout=10 max-mru=1480 max-mtu=1480 max-sessions=0 mrru=\
disabled one-session-per-host=yes service-name=XXXX
set default change-tcp-mss=yes comment="" name=default only-one=default use-compression=default \
add change-tcp-mss=yes comment="" dns-server=10.120.0.2,10.120.0.3,10.120.128.2 local-address=\
200.xxx.xxx.xxx name=PPPoE only-one=default remote-address=POOL-PPPoE use-compression=default \
use-encryption=default use-vj-compression=default wins-server=127.0.0.1
If someone likes to see more information, please ask.